This invention relates to heddle frames for weaving looms and more particularly to improvements in their construction in the attachment of heddle supporting rods to the heddle frames.
Heretofore, it has been common in the weaving art to employ heddle frames having rods on which the heddles are mounted. These rods are typically made of steel strips with a cross-section which facilitates mounting on the frame and on which the end eyes of the heddles are freely movable. An illustration of such heddle rods is in U.S. Pat. Nos. 3,417,788 and 4,106,529. These patents show the heddle rods being riveted at their faces to the heddle frame slats and joined at their end to the side struts of the heddle frame.
During shedding operations on a weaving loom, the heddle frame reciprocates vertically in rather short, rapid strokes with the warp yarns threaded through the center eye of the heddle. The warps are thus lifted up and down. The dynamic forces on the heddle frames and their assembly parts are large during the shedding motions. With the advent of high speed looms, such as water-jet looms, the vertical reciprocation of the heddle frame occurs at even higher speeds resulting in even larger accelerations and dynamic forces on the heddle frame. Thus, the parts and connections in the heddle frame assembly are subjected to larger stress and fatigue forces than ever encountered in shuttle looms. This has required more reliable and accurate construction of the heddle frame assembly to eliminate weak spots.
In particular, the heddle rods have been, heretofore, riveted to the slats of the heddle frame by conventional methods in which a countersink opening is formed in the face of the heddle rod and the corresponding surface of the heddle frame slat against which the rod mates. A rivet is peened or headed on both ends within the countersink openings to form a conventional rivet connection between the members. However, inaccuracies in the heddle rod thickness and rivet countersink dimensions make this type of connection susceptible to failure. These dimensions are critical since the rivet is of a fixed length and amount. If any of these dimensions are beyond acceptable tolerances, the rivet material either fills the opening too much or too little. If the countersink opening is too small, excess rivet material forms a protruding rivet head which impairs free heddle travel over the face of the rod. If the opening is too deep, the rivet material either does not fill the opening completely or too much rivet material is used in the opening leaving an insufficient amount in the other opening resulting in an imperfect rivet head and weak connection.
Furthermore, even a properly headed rivet connection allows wobbling of the heddle rod about the connection which, after prolonged use, can become attenuated and lead to failure. The end eyes of the heddles often engage the rivet head exposed on the face of the heddle rod causing excess wear therebetween which leads to loosening of the rivet head.
Typically, the rivet must be held with a serrated anvil to prevent the rivet from turning during peening which can cause improper heading. However, deterioration of the serrated anvil also reduces the integrity of the rivet head connection.